The invention relates to a method of forming a wear and scratch resistant protective layer on a surface of a support, where the protective layer comprises at least a first surface area and a second surface area, the surface areas are distinguishable by virtue of the fact that the surface areas differ from each other in at least one visual property, and the method further comprises:
partially masking parts of said support outside said first surface area with a mask layer which partially covers the support, and
subjecting the support to an electrochemical treatment, wherein the first surface area of the protective layer is formed in non-masked parts of the support.
Such a method, and such an object, are disclosed in U.S. Pat. No. specification 3,284,321. In accordance with said patent specification, a surface is partially provided with a mask and subsequently electrochemically treated by anodizing it. Only the first, non-masked area of the surface is provided with an anodized layer. As described in said patent specification, the anodized area of the surface is subsequently sealed, so that it is no longer porous. Next, the mask is removed, for example by means of a solvent, and the surface is re-anodized. As the surface area anodized during the first anodizing treatment is sealed, the second anodizing treatment has little or no effect on the surface area anodized during the first anodizing treatment.
In this manner, a surface is obtained comprising two or more optically different areas, which surface is wear and scratch-resistant, and protected against chemical attack, said surface additionally being visually attractive. Also the anodized layer formed during the second anodizing treatment is preferably sealed.
As a result of said properties, electrochemically treated surfaces, such as anodized and chrome-plated surfaces can very suitably be used as the outer layer of parts of utensils which are subjected to intensive contact with users, such as housing parts of, in particular shaver heads, of shavers (in this respect, also the resistance to solvents and compositions for personal care such as shaving lotions, shaving soap and the like is important), control buttons, gear lever knobs, handles, clasps of bags and suitcases, and stationery.
However, the removal of the mask and the re-anodizing treatment are laborious. In addition, the use of solvents to remove masks requires special measures to preclude emissions of volatile solvents into the environment and to preclude excessive exposure of employees to such volatile solvents.
It is disclosed in U.S. Pat. No. specification 3,450,606 to partially anodize and color surfaces by first anodizing the whole surface and, if necessary, coloring it, after which parts of the anodized and, possibly, colored surface are partially masked, whereafter the anodized layer is etched from the non-masked parts and, subsequently, the surface is again immersed in an anodizing bath, whereby the etched parts are anodized in a second color. Also these anodized surfaces can be masked, partially etched and anodized in a different color. Repeatedly anodizing, masking, etching and re-anodizing is laborious and hence expensive.
U.S. Pat. No. specification 3,284,321 and German patent application 23 63 667 both describe the application of a resist onto the areas of a surface that are not to be anodized, after which the surface is anodized and, next, the resist is removed by immersing in a bath. Also in this case, the removal of the resist after the anodizing treatment is laborious. In addition, the initially masked surface region is not provided with a protective layer.
Japanese patent application 62-278277 describes a similar method of partially anodizing a surface, wherein, in addition, the surface is provided with a transparent protective film which covers the anodized and the non-anodized parts of the surface. The application of such a resist requires an additional operation and generally results in a not entirely satisfactory resistance to attack when an object coated with such a resist is intensively used.

It is an object of the invention to obtain, in a simpler manner, a wear and scratch-resistant protective layer which comprises at least two visually distinguishable types of surface areas.
In accordance with the invention, this object is achieved by using a method in which a sol-gel layer is provided as the mask layer, and forms the second surface area of the protective layer.
In this manner, as a result of masking, also the second surface area of the intended, highly wear and scratch-resistant protective layer is obtained. Consequently, to obtain the protection in the second surface area, an additional stripping treatment and/or electrochemical treatment is no longer necessary.
In addition, the sol-gel layer is substantially intact after electrochemical treatments, such as anodizing and, possibly, sealing, and also along the edges there is no substantial attack due to creep under the sol-gel layer. As a result, the support can be provided with a clear-cut, visually attractive pattern.
In the course of the electrochemical treatment, the sol-gel layer serves as an isolator, so that said electrochemical treatment is not effective in the masked area. This applies to treatments in which material is converted, such as an anodizing treatment, as well as to electroplating treatments in which material is deposited, such as zinc-plating, nickel-plating, chrome-plating and tin-plating.
Particularly advantage embodiments of the invention are described in the dependent claims.